In endometriosis, numerous studies have evaluated polymorphisms in genes involved in estrogen biosynthesis and metabolism, such as CYP17A1 [59] and COMT [60], as well as variants in the PGR gene [61], inflammatory cytokines (e.g., interleukin 6 (IL-6); tumour necrosis factor (TNF-α)), and extracellular matrix remodelling enzymes, including members of the matrix metalloproteinase family (MMPs) [62]. The gene discussed is COMT; the disease is endometriosis.